Renaming Files with Bad Characters

Question

I'm not sure what I'm doing wrong here, but when I try to Rename-Item with a new filename I keep running into an error saying the original file that I want to rename does not exist. My goal is to remove multiple "bad" characters from the given file name. Bad characters are []<>:* and I'm only currently looking at [] to make sure it works before adding the rest.

Code Example:

$Directory  = "G:\TEMP\2016\"
$ExcelFiles = Get-ChildItem $Directory -Recurse -Include *.xls,*.xlsx |
              % {$_.FullName}

foreach ($excelfile in $excelfiles) {
    #Write-Host "Checking $excelfile"

    if ($excelfile -match "\[|\]") {
        $newfilename = $excelfile -replace "[\[\]]", ""
        Rename-Item $excelfile -NewName $newfilename
    }
}